Grinding mills are used to process hard solid material such that the solid material is crushed into smaller pieces. The grinding mills comprise a rotatable drum having a cylindrical wall and the interior of the drum is used for processing the solid material. The interior wall of the drum is equipped with lifter bars and as the drum rotates the lifter bars lift up the solid material along the inside wall of the drum to a point where gravity causes the solid material to fall down inside the drum and by falling down the solid material is crushed.
The lifter bars' function is to assist in lifting the solid material being processed up the side of the drum as it rotates. The lifter bars are typically made of rubber or elastomer so during time the lifter bars become worn and they have to be replaced by new ones. The lifter bars become worn from the wearing surface and especially from the leading face of the lifter bar, the leading face being the upstream side of the lifter bar which is at least partially facing the predetermined direction. The extent of the leading face of the lifter bar depends on the form of the lifter bar but it is the part of the lifter bar which contacts the solid material when the solid material is lifted up to the point from which it falls down. When the leading face of the lifting bar wears over time because of the continuous impact of the solid material the lifting effect becomes less and the efficiency of the grinding mill diminishes. The lifter bars may have to be replaced with new ones about every six months.
The following discussion of the prior art is intended to present the invention in an appropriate technical context and allow its significance to be properly appreciated. Unless clearly indicated to the contrary, however, reference to any prior art in the specification should not be construed as an admission that such art is widely known or forms part of the common knowledge in the field.
US 2012/0181364 A1 discloses a mill liner assembly to be mounted on a shell of a grinding mill. The mill liner assembly includes shell plates and lifter bars having a mounting portion. The publication discloses a problem that while the lifter bars and shell plates become worn they have to be replaced quickly and separately and for this purpose a new way of mounting of said assembly is developed.
One of the disadvantages associated with the above arrangement is that when the lifter bars become worn they have to be replaced with new ones and the old lifter bars are waste that has to be disposed. The replacement of lifter bars with new ones is a necessary but expensive part of maintenance of a grinding mill and the disposal of the worn lifter bars add costs on top of that. There is also an environmental aspect relating to the used lifter bars because over time the amount of waste material becomes quite considerable.